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ADD: delete method and set length property to NativeJavaList #1031

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merged 2 commits into from
Oct 14, 2021
Merged

ADD: delete method and set length property to NativeJavaList #1031

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9931a30
ADD: delete method and set length property to NativeJavaList
rPraml Sep 17, 2021
917426d
ADD: JavaDoc / using list.add if last element is added
rPraml Sep 21, 2021
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29 changes: 29 additions & 0 deletions src/org/mozilla/javascript/NativeJavaList.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,12 @@ public boolean has(int index, Scriptable start) {
return super.has(index, start);
}

public void delete(int index) {
if (isWithValidIndex(index)) {
list.set(index, null);
}
}

@Override
public boolean has(Symbol key, Scriptable start) {
if (SymbolKey.IS_CONCAT_SPREADABLE.equals(key)) {
Expand Down Expand Up @@ -87,6 +93,15 @@ public void put(int index, Scriptable start, Object value) {
super.put(index, start, value);
}

@Override
public void put(String name, Scriptable start, Object value) {
if (list != null && "length".equals(name)) {
setLength(value);
return;
}
super.put(name, start, value);
}

private void ensureCapacity(int minCapacity) {
if (minCapacity > list.size()) {
if (list instanceof ArrayList) {
Expand All @@ -98,6 +113,20 @@ private void ensureCapacity(int minCapacity) {
}
}

private void setLength(Object val) {
double d = ScriptRuntime.toNumber(val);
long longVal = ScriptRuntime.toUint32(d);
if (longVal != d || longVal > Integer.MAX_VALUE) {
String msg = ScriptRuntime.getMessageById("msg.arraylength.bad");
throw ScriptRuntime.rangeError(msg);
}
if (longVal < list.size()) {
list.subList((int) longVal, list.size()).clear();
} else {
ensureCapacity((int) longVal);
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This seems dangerous since typical java Lists don't support sparse layouts like javascript arrays do. If you set length to a very large value on a javascript array it's no big deal, but do the same on an ArrayList, and you're probably going to run out of memory.

Should we at least add a javadoc description for the class that describes the additional behaviors which NativeJavaList adds to NativeJavaObject and potential pitfalls when using these features as if Lists were arrays? Is this stuff documented anywhere else other than in PRs and commit messages?

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Improving the Javadoc sounds great to me.

In general, the "embedding guide" is very very old and hasn't it been archived by Mozilla? Do we have any volunteers to resurrect it?

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How should we document this? JavaDoc, MD, wiki-page?

I would prefer a markdown documentation like this one: https://github.com/oracle/graaljs/blob/master/docs/user/JavaInteroperability.md

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Personally, I think the javadoc should contain basic important information for using the class. Wiki/user guide type documentation is good for going into more detail if someone is willing to write that. As we know, external documentation is not always easily accessible and developers should have some idea how a class works without having to closely study the code or pull up external docs.

}
}

@Override
public Object[] getIds() {
List<?> list = (List<?>) javaObject;
Expand Down
67 changes: 65 additions & 2 deletions testsrc/org/mozilla/javascript/tests/NativeJavaListTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
import junit.framework.TestCase;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.ContextFactory;
import org.mozilla.javascript.EcmaError;
import org.mozilla.javascript.NativeArray;
import org.mozilla.javascript.Scriptable;
import org.mozilla.javascript.tools.shell.Global;
Expand Down Expand Up @@ -65,6 +66,10 @@ public void testLengthProperty() {
list.add(2);
list.add(3);
assertEquals(3, runScriptAsInt("value.length", list));
runScriptAsInt("value.length = 6", list);
assertEquals(6, list.size());
runScriptAsInt("value.length = 2", list);
assertEquals(2, list.size());
}

public void testJavaMethodsCalls() {
Expand All @@ -83,8 +88,9 @@ public void testUpdatingJavaListIntegerValues() {
list.add(3);

assertEquals(2, runScriptAsInt("value[1]", list));
assertEquals(5, runScriptAsInt("value[1]=5;value[1]", list));
assertEquals(5, list.get(1).intValue());
// setting values in lists will set them as double
assertEquals("5.0", runScriptAsString("value[1]=5;value[1]", list));
assertEquals(5.0, list.get(1));
}

public void testAccessingJavaListStringValues() {
Expand All @@ -108,6 +114,63 @@ public void testUpdatingJavaListStringValues() {
assertEquals("f", list.get(1));
}

public void testAutoGrow() {
List<String> list = new ArrayList<>();
// Object list = runScript("[]", null, Function.identity());
assertEquals(0, runScriptAsInt("value.length", list));
assertEquals(1, runScriptAsInt("value[0]='a'; value.length", list));
assertEquals(3, runScriptAsInt("value[2]='c'; value.length", list));
assertEquals("a", runScriptAsString("value[0]", list));
// NativeArray will have 'undefined' here.
assertEquals("null", runScriptAsString("value[1]", list));
assertEquals("c", runScriptAsString("value[2]", list));
// NativeList will return "a,,c"
assertEquals("a,,c", runScriptAsString("Array.prototype.join.call(value)", list));
}

public void testLength() {
List<String> list = new ArrayList<>();
list.add("a");
list.add("b");
list.add("c");
runScriptAsString("value.length = 0", list);
assertEquals(0, list.size());
runScriptAsString("value.length = 10", list);
assertEquals(10, list.size());

try {
runScriptAsString("value.length = -10", list);
fail();
} catch (EcmaError e) {
assertEquals("RangeError: Inappropriate array length. (#1)", e.getMessage());
}

try {
runScriptAsString("value.length = 2.1", list);
fail();
} catch (EcmaError e) {
assertEquals("RangeError: Inappropriate array length. (#1)", e.getMessage());
}

try {
runScriptAsString("value.length = 2147483648", list); // Integer.MAX_VALUE + 1
fail();
} catch (EcmaError e) {
assertEquals("RangeError: Inappropriate array length. (#1)", e.getMessage());
}
}

public void testDelete() {
List<String> list = new ArrayList<>();
list.add("a");
list.add("b");
list.add("c");
// Object list = runScript("['a','b','c']", null, Function.identity());
// TODO: should NativeJavaList distinguish between 'null' and 'undefined'?
assertEquals("false", runScriptAsString("delete value[1]", list));
assertEquals("a,,c", runScriptAsString("Array.prototype.join.call(value)", list));
}

public void testKeys() {
List<String> list = new ArrayList<>();
NativeArray resEmpty =
Expand Down